Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations cover the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=false), and the description adds meaningful behavior beyond them: no signup required, key scoping semantics via service.name, and that the webhook receives an HMAC-signed POST on band changes. It does not say whether the returned key is shown only once or whether creation is idempotent.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two tight sentences with the key facts front-loaded: identity, scope, then the optional parameter. Nothing is padded, though the fragment style ('(no signup)') reads slightly like marketing rather than specification.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a creation tool with no annotations gaps and full schema coverage, the description is mostly sufficient, but it never says what the call returns — presumably the key/secret value — which is the single most important thing an agent needs, especially if the key is only displayed once. No output schema exists to cover this.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% and the single parameter is documented, so baseline is 3; the description earns above baseline by explaining what the webhook actually does (HMAC-signed POST on band change) and that it is recommended, not merely optional. It does not add format/validation detail beyond the https note already in the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Create a scoring key') and adds a distinguishing constraint ('no signup') plus the key's scope ('One key covers all agents, identified by OTel service.name'). It is clear apart from the sibling set, though it does not explicitly contrast with revoke_key or set_webhook.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Useful context is implied — one key per service.name, webhook optional but recommended — but there is no explicit guidance on when to call this versus set_webhook (which presumably attaches a webhook later) or whether the webhook can be added post-creation. The agent must infer.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.